DES MOINES, Iowa — After nearly 40 years in prison for a 1974 shooting outside a Waterloo pool hall, Rasberry Williams is a free man.

The Iowa Board of Parole decided Wednesday to parole Williams, 68, after Gov. Terry Branstad commuted Williams's life sentence last spring based on reports Williams was a model inmate who prevented two inmate attacks on correctional officers.

"I'm very grateful today," Williams said, appearing on closed-circuit television from the North Central Correctional Facility in Rockwell City.

Williams was convicted of shooting Lester Givhan, 40, on July 20, 1974, after the men argued over a $30 gambling debt.

Givhan allegedly offered Williams the money, then pulled it back when Williams reached for it. Williams drew a revolver and fatally shot him, authorities said. Williams claimed self-defense, saying Givhan, who had a criminal history, appeared to be going for a gun.

Williams told the parole board he wanted to live with his sister on the south side of Chicago, but the board decided the aging man who walks with a cane should go to an assisted living center in Waterloo or Dubuque. His parole will last the rest of his life.

Branstad commuted Williams's prison sentence from life without parole to life with the possibility of parole. The Parole Board reduced Williams's supervision last year, moving him to the minimum-security prison in Rockwell City in September.

Commutation is rare in Iowa, with governors reducing the legal penalty for only 30 people in the last 44 years. Most of the commutations cut mandatory life sentences to fixed-length terms with a possibility of parole.

Branstad has commuted the life prison terms of just two other inmates in his 18 years in office. One of those, Rubben Jones, 64, of Des Moines, told The Gazette in April 2013 he thought Williams deserved another chance.

"Thirty to 40 years of your life, I know it can't replace a life that has been taken, but I think he's suffered enough," Jones said.

Branstad has denied commutations for more than 30 people in 2013 and 2014 so far.